README on npmjs.org is incorrect and inconsistent with README here in master

[newhouse]

The README for this package on npmjs.org is not the same as the README here in the repo. The versions are the same, however, it looks like when the examples and README were updated here, they were not pushed to NPM. Specifically, the NPM docs are still showing primus.use('rooms', Rooms); when they should be showing primus.plugin('rooms', Rooms);.

This really cost me a lot of time by following the example off of the NPM website and finding it not working. I almost bailed on Primus and it definitely made me nervous about it.

I'd suggest a patch or whatever to get the changes to take affect in NPM. Thanks!